To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition of 70 (VF-). This indicates that it is in an acceptable state, but not of high quality. In the past, coins with a similar condition have had auction prices that vary, but are generally lower than those in better condition.

2. Auction History:
- The average hammer price for similar coins has been 109.96 euros.
- In previous auctions, coins with a condition of 70 have had hammer prices ranging from 12 to 54 euros, depending on other factors such as demand and rarity.

3. Starting Price: The starting price is 12 euros, which suggests that the auction house expects moderate interest in the coin.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have shown a range that can reach up to 70-80 euros, but this depends on demand at the time of the auction.

5. Estimation Based on Historical Data: Given that the average hammer price is 109.96 euros, but considering the condition of 70 and the historical hammer price for coins in similar conditions, an estimated maximum purchase price could be between 50 and 80 euros.

Conclusion: Based on all these factors, an estimated maximum purchase price for this coin could be approximately 70 euros. This reflects a balance between the current condition and the historical hammer prices.